Why does Pinkie Pie have a strong relationship with Rainbow Dash? - Sugarcube Corner - MLP Forums

I always wondered why Pinkie Pie and Rainbow Dash have such a strong friendship?

MLP Next Gen: Pinkie Pie x Cheese Sandwich PREVIEW by PokemonTrainerMax on DeviantArt

Equestria Daily - MLP Stuff!: Pony Community Soapbox #152 - Unhelpful Princesses, Cheerilee Episodes, and More!

The Support of a True, True Friend - Pinkie Pie Awareness - Fimfiction

My Little Pony: 10 Best Pairings In The Entire Series

Favorite Color Swapped Ponies? - Sugarcube Corner - MLP Forums

Pinkie Pie: Toilet Diver - Fimfiction

My Little Pony: Friendship Is Magic S4 E12 Pinkie Pride / Recap - TV Tropes

Pinkie Pie (redesign) by CapriNin on DeviantArt

Equestria Daily - MLP Stuff!: 50+ Awesome Rainbow Dash Fanfics to Read for RD Day!